Introduction
Carbon molecular sieve is a new kind of adsorbent and an excellent non-polar carbon material. The main component of carbon molecular sieve is elemental carbon, the appearance is black columnar solid, containing a large number of 0.28-0.36nm diameter of micropores and a small number of large and medium pores (also known as transition holes), as shown below, the specific surface area of its micropores accounts for more than 90% of all pore surface area of carbon molecular sieve, micropore specific surface area generally exceeds 1000m2/g level.

The ability of CMS to separate air depends on the different diffusion rates of oxygen and nitrogen in the air in the carbon molecular sieve micropores. Due to the difference in the relative diffusion rates of gas molecules with different kinetic diameters, the components of the gas mixture can be effectively separated. The internal micropore distribution of commonly used carbon zeolite should be 0.28 ~ 0.36nm. In the micropore size range, oxygen (kinetic diameter 0.346nm) can quickly diffuse into the pore through the micropore port, while nitrogen (kinetic diameter 0.364nm) is more difficult to pass through the micropore port, so as to achieve oxygen and nitrogen separation. Carbon dioxide (kinetic diameter 0.33 nm) can also be rapidly diffused through the pore orifice into the pore, and is a relatively strong adsorbed gas.